In the production of fried food products, the quality of the oil used for frying the products is directly linked to the quality of the final product. Corn and potato products such as potato chips and corn chips shed particulates during the frying process.
When these particulates or crumbs accumulate in the frying oil, if they are not promptly removed there will be breakdown in the quality of the oil and the product as evidenced by an increase in free fatty acids in the oil, discoloration of the oil, plugging of heat transfer surfaces, and a reduction in the quality of the product it produces. Prompt removal of the particulates dramatically improves the quality of the oil and of the product compared to what their condition would be if the particulates were not removed.
One simplistic solution is to filter the oil and change it frequently. There are several problems with this approach. For one these production facilities are generally operated on a 24 hour basis, and shutdown time is both inconvenient and expensive. In fact, a full shutdown and servicing may require 24 hours.
For another, these facilities use large quantities of oil. It is not unusual for a fryer to contain 1,500 gallons of oil. Unnecessarily frequent changes of the oil are very costly.
As still another problem, the frying temperatures are often as high as 420 degree, and the flow of hot oil through the heat exchanger and flow system is under pressure. The continuous removal of crumbs from known operating systems tends to expose the operator to exposure of hot pressurized oil. This is an undesirable risk which this invention averts, while still providing filtration of 150 micron particulates.
In fact it is an object of this invention to enable continuous filtration and removal of cooled particulates without exposing personnel to hot or pressurized oil or to particulates in such a way that the ultimate change of oil can be deferred from the presently-accepted six day cycle to a 21 day cycle, while still maintaining good quality oil and product. This equates to an extra 44 days of production per year, approximating a 15% increase in production capacity for an installation.
It should be kept in mind that the operation of this process is continuous. The fryers receive the raw product on a conveyor, which carries it through the hot oil, and removes it from the oil, thereafter to be drained, cooled and packaged. Some oil is carried out of the apparatus as part of the product, and makeup oil is added to replace it. The particulates (crumbs) are separated as part of the filtration process. After filtration the oil is returned to the fryer along with any makeup oil.
One of the most troublesome parts of the cooker system is the heat exchanger in which the oil is heated. It is a recirculating arrangement usually utilizing externally heated tubes through which the oil flows to be heated. These tubes are the hottest part of the system, and crumbs can tend to cake and coat its internal surfaces and plug the tubes. The system of this invention consistently removes particulates of such small size that deposition on the tubes is long deferred compared to known systems, and when it is flushed out in the servicing operation, it is readily removed.
To service any hot oil system requires that the pressure be reduced to ambient, and the temperature be cooled to an acceptable value. This takes time and significantly reduces the production capacity of the system. Allowing servicing to proceed at higher temperatures, and before the pressure has vented can subject the service personnel to risk of injury.
It is an object of this invention to provide a system which enables continuous frying to occur while filtration continues, and which permits particulates to be removed through a system that protects service personnel from risk, and can be done without shutting down the entire system.